The permanence of printed documents and books appears to be primarily
dependent on paper stability. Other researchers implicate pH as a major
factor in the deterioration rate of paper and acidity as major the cause
of this deterioration. During the lithographic printing process, ink is
in direct contact with fountain solution, which can be acidic or alkaline.
Fountain solution is a mixture of water and chemicals used to keep the
non-image areas of a lithographic plate moist. On press the intimate
contact of ink with fountain solution creates a fountain solution-in-ink
emulsion. The emulsion used here is a stable suspension of fountain
solution droplets within the ink. The objective of this study was to
determine if ink/fountain solution emulsion, which is printed on paper
during lithographic printing, affects the rate of deterioration of paper.
The stability of four commonly available papers was observed. These
paper types were groundwood, publication grade, coated book, and uncoated
book. Samples of the four paper groups were printed with four different
ink formulations. The ink formulations were ink, ink and distilled water,
ink and acidic fountain solution, and ink and alkaline fountain solution.
Samples of the unprinted and printed paper were subjected to an
accelerated - aging process by heating the samples for 72 hours at
100 C. The properties of unaged and aged papers were evaluated by pH
determination, folding endurance, and tearing resistance. On the basis of
statistical analysis of the data, inferences were made about the effect of the ink formulations on the paper properties.
This experiment indicates that ink/fountain solution emulsion did
affect the paper pH, but this effect is due to the ink with little change
in pH due to the addition of acidic or alkaline fountain solution to the
ink. The results of folding endurance and tearing resistance tests after
accelerated aging established no clear pattern of variance that would
indicate the differences observed in these properties were due to the pH
change associated with the ink/fountain solution emulsions. Several
unexpected occurrences were exhibited by this experiment. These include:
groundwood was the paper least affected by the aging process; the pH of
coated paper increased with the application of ink/fountain solution
emulsion; a decrease in tearing resistance was associated with alkaline
fountain solution.